Anti-suffocant apparatus for oxygen supply systems



June 15, 1965 BARTLETT, JR 3,189,027

ANTI-SUFFOCANT APPARATUS FOR OXYGEN SUPPLY SYSTEMS Filed Nov. 29, 1962OXYGEN 44 SUPPLY INVENTOR.

Roscoe G. B lefl, Jr. BY

gasping will likewise open this valve.

United States Patent Ofiice 3,189,927 Patented June 15, 1965 3,139,027ANTI-SUFFQCANT APPARATUS FQR OXYGEN SUPPLY SYSTEMS Roscoe G. Bartlett,Jr., Lime Kiln, Md.

Filed Nov. 29, 1962, Ser. No. 241,083 Claims. (Cl. 128-142) (Grantedunder Title 35, U.S. Code (1952), see. 266) The invention describedherein may be manufactured and used by or for the Government of theUnited States of America for governmental purposes without the paymentof any royalties thereon or therefor.

The present invention relates generally to apparatus for sustainingflight personnel exposed to environments the oxygen content to which isinsufficient for their normal respiratory requirements and, moreparticularly, to a safety attachment for an oxygen pressure mask whichautomatically permits the wearer to inspire air from the localatmosphere when his oxygen supply has been expended. V

In one type of conventional oxygen supply system for high altitude use,oxygen in one mode of operation is delivered to the facemask underpressure to ease the wearers respiratory efforts. However, when theoxygen supply is depleted, the individual usually must remove his maskbefore he can inspire air from the surrounding atmosphere. If he isunconscious or otherwise disabled at this time, he may, of course,suffocate, notwithstanding the fact that he may be in an environmentwhich can satisfy his oxygen requirements.

It is accordingly a primary object of the present invention to providean attachment for a facernask of the type used in an oxygen supplysystem which automatically switches the mask from the oxygen source whenthe supply of oxygenis exhausted to the local atmosphere.

Another object of the present invention is to provide a lightweight,compact, safety bypass valve that can be mounted on a conventionaloxygen-pressure facemask so as to automatically couple the mask to thelocal environment when the oxygen supply is depleted.

A yet still further object of the present invention is to provideapparatus for use with an oxygen mask which functions even when theindividual wearing the mask is unconscious to switch the input torthemask from the oxygen supplywhen this supply is used up to the localatmosphere.

A yet still further object of the present invention is to provide asafety. feature for an oxygen mask used in a pressure-breathing systemwhich responds to the wearers respiratory action to effectively couplethe mask to the local atmosphere when the oxygen supply in thesystem isexpended.

Briefly and in somewhat general terms, the above objects are realized inone embodiment of the invention by attaching a lightweight, compact,safety bypass valve to the breathing tube section of a facemask designedfor pressure breathing. As long as there is a flow of oxygen from theoxygen supply source into the facemask, this bypass valve remains in itsclosed position. However, when the oxygen supply is exhausted, thewearer's inhalation elforts by themselves automatically open the bypassvalve, thereby coupling the local atmospheric environment to thebreathing tube section of the facemask. If the individual in unconsciousat this critical time, his A snap-acting mechanism is included in thevalve assembly to give it a positive type of action. Additionally, theapparatus has a reset device which permits the wearer to manuallycontrol the condition of the bypass valve.

Other objects, advantages and novel features of the invention willbecome apparent from the following detailed description of the inventionwhen considered in con junction with the accompanying drawings wherein:

FIG. 1 schematically illustrates one embodiment of the present inventionapplied to a facemask designed for pressure breathing; and

FIG. 2 shows the details of a part of the snap-acting feature of thesafety bypass valve of FIG. 1.

Referring now to FIG. 1 of the drawings, which illustrates theapplication of the present invention to an oxygen supply system forflight personnel, a conventional facemask 1, designed for pressurebreathing and fabricated of molded rubber, .for example, is provided ata lower portion thereof with a flexible breathing tube section 2 and anexhaust port 3. In the particular mask configuration selected forillustration, only the nose and mouth of the wearer are covered.However, it should be readily appreciated that additional coverage maybe included for the complete head of the wearer. Breathing tube section2 in one design is closed at'its remote end by a wall 4 which has acentral aperture formed therein through which passes nozzle 6 of aconventional pressure-compensated exhaust valve 7.

In one prior art construction, this exhaust valve has as its controldevice a piston 11 which is normally biased by coil spring 12 to itsclosed position up against valve seat 13. Nozzle 6 leads to the bottomside of this piston and, as will be seen hereinafter, prevents thisvalve from opening except during the exhalation portion of the wearersbreathing cycle. This valve is mounted in a transverse wall 8 whichpartitions off the bottom portion of the mask from the facemask area.Also built into this mask are a pair of air passageways 9, only one ofwhich is shown, which lead from breathing tube section 2 into the facemask area. Each of these passageways terminates in a nonloaded checkvalve which allows only acne-way gas flow into the facemask area.

In the normal operation of the oxygen supply system, oxygen from thehigh pressure supply source, after a pressure reduction, flows intobreathing tube section 2 through passageways 9 and check valves 10 intothe respiratory system of the individual wearing the facemask. Duringthe expiratory portion of the latters breathing cycle, his dischargeopens exhaust valve 7 and passes via exit port 3 out into theatmosphere.

The anti-suffocant bypass valve of the present invention, generallyrepresented by reference character 14, is attached to the breathing tubesection 2 of the facemask by a suitable clamping device 15. Bypass valve14 includes a housing 16 which is closed at its top portion by a coverplate 17 that has a plurality of ports 18 cut therethrough at onelocation and a single aperture 19 formed therein at a second location.Clamping device establishes an airtight fit between the lower portion ofbreathing tube 2 and a sleeve 16 which locks into the latter aperture.

Mounted on the top surface of cover plate 17 is a sleeve 20 whose innertop wall portion is threaded 'to receive a cap 21. This sleeve has anexternal flange 22 formed at its lower end which is locked under aclamping plate 23 that is fastened by suitable screws 24 to the top wallof housing 16. Closure cap 21 has a plurality of apertures 25 and acentralaperture 26 formed in its central top wall portion. Passingthrough the latter aperture and through cover plate 17 is a push orreset rod 27 which is secured at a point intermediate its length to acircular piston 28.

Also positioned within sleeve 20 is an elastic bellows 29 which fitsinto a cutout portion formed in the bottom rim of cap 21. When piston 29is in its upper or closed position, it compresses bellows 29 and formsan airtight seal with the bottom end thereof. A bias spring 30 is alsoincluded in the apparatus with its top portion abutting the bottom wallof cap 21 and its bottom portion resting on piston 29. This spring,which controls the opening pressure of the safety bypass valve, hasinsufiicient force by itself to move piston 23 downwardly to unseat itfrom element 29 whenever a positive pressure exists within housing 16.

It would be pointed out that push rod 27 is free to move up and downthrough the apertures in closure cap 21 and cover plate 17 and, whenit-does so, piston 28 moves along with it. When piston 28 movesdownwardly from the position shown, the contact between its peripheralsurface and the lower rim of bellows 29 is not immediately brokenbecause of the expansion of bellows 29. This action, as will be seenhereinafter, insures the positive opening of the bypass valve,

When piston 28 finally does break contact with the lower rim of bellows29, air can be drawn from the outside atmosphere through ports 25 intothe top half of sleeve 20, around the rim of piston 28 into the bottomhalf of the sleeve, and thence via apertures 18 into the central portionof housing 16. From here it can pass directly into the breathing tubesection 2 and the face mask area.

As best shown in FIG. 2, push rod 27 has a slot 31 cut therethrough nearits bottom end. Passing through this slot and extending a short distancebeyond is a lever 32 which is mounted for pivotable movement about ashaft 33 journalled into a pair of ears 34 formed in a post 35 thatextends upwardly from the bottom wall of housing 16. Lever 32 carries atits remote end a cross bar 36, and a pair of springs 37 under tensionare connected between the ends of this bar and a pair of extension arms38 projecting from both sides of post 35. It will be recognized thatlever 32 and its affiliated spring components constitute a snap-actingmechanism that positively displaces piston 28 to either its open orclosed condition once this lever passes over its center or horizontalposition.

Secured to the bottom wall of housing 16 is a pressure reducer 39 whichfunctions to reduce the oxygen pressure to a level that is not injuriousto the respiratory system of the individual. Pressure reducer 39, whichis of conventional design, produces a low pressure flow from its outputside into the central portion of housing 16 via a plurality of apertures41 and a smaller flow into nozzle 6 of pressure-compensated valve 7 viaits nozzle 42 and a flexible tubing 43 connected therebetween. This lastconnection provides the pressure compensation for exhaust valve 7 andprevents the oxygen normally flowing into the facemask area viabreathing tube section 2, passageways 9 and check valves from depressingpiston 11 and thus passing out unused into the atmosphere via exit port3.

The operation of the apparatus of FIG. 1 is as follows: To prepare theequipment for use, push rod 27 is first moved to the position shown,thereby closing the antisuffocant bypass valve 14. When pressure ordemand breathing is initiated, oxygen flows from source 44 via line 40,out of ports 41 into the breathing tube section 2 of the facemask and,thence, via passageways 9 and check valves 10 into the respiratorysystem of the individual. During the expiratory portion of his breathingcycle, his discharge opens pressure-compensated valve 7 and passes viaport 3 out into the atmosphere. The oxygen flow from ports 41 alsomaintains a positive pressure within the central portion of housing 16,and this pressure, acting upon the bottom surface of piston 28, insuresthe closed condition of bypass valve 14. Thus, the oxygen breathingsystem is isolated from the atmosphere except during the exhalationportion of each breathing cycle.

When the oxygen source is depleted, the individual depresses push rod 27downwardly to open bypass valve 14 and allow air from the outsideenvironment to enter the facemask to satisfy his breathing demands.However, if he is unconscious or otherwise disabled at this time, hiscontinued breathing action will also bring about the same result becausethe negative pressure developed by his gasping will first open checkvalves 10 and then bypass valve 14. More paiticularly, when hisbreathing efforts create a negative pressure within housing 16, piston28 is pulled downwardly until lever 32 passes just beyond its center orhorizontal position. Spring 30, of course, assists this action. Aspiston 28 moves downwardly, elastic bellows 29 expands and, in effect,follows the piston to hold the valve closed until lever 32 moves beyondthe above position. If this bellows were not present, as soon as piston28 moved off its seat the pressure would fall and the valve would not goover center to stay open. Once lever 32 moves beyond the over centerposition, springs 37 act to snap piston 28 quickly to its completelyopen position and lock it in this condition. With bypass valve 14 nowopen, air from the outside can be drawn via ports 25 and 18 into housing16 and thence via breathing tube section 2 and facemask 1 into theindividuals respiratory system.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

What is claimed is:

1. An anti-sulfocant safety valve for an oxygen supply system of thetype wherein oxygen from a supply source enters a supply line leadinginto the interior of a facemask comprising, in combination,

a chamber;

a sleeve connected to an exterior wall of said chamber and having oneend thereof communicating with the interior of said chamber;

a piston positioned within said sleeve and having a diameter less thanthe interior diameter of said sleeve:

an over-center, snap-acting switching mechanism connected to saidchamber and to said piston for moving said piston between an upper andlower position within said sleeve;

a bellows open at both ends thereof;

said bellows having one end thereof connected to the top of said sleeveand the other end extending downwardly to a position slightly beyond themid-point between the upper and lower positions of said piston wherebysaid bellows contacts said piston to form an airtight seal therewithfrom the upper position of said piston to a position slightly beyondsaid midpoint and is spaced from said piston When said piston in in itslower position,

and means defining an air passageway between said chamber, said supplysource and said supply line whereby whenever a negative pressure iscreated in said supply line in response to the inhalation efforts of anindividual wearing said facemask, said piston is drawn downwardly fromits upper position until said over-center, snap-acting switchingmechanism suddenly activates it to its lower position whereby air fromthe atmosphere can thereafter be drawn through said sleeve and into saidchamber for use by the individual wearing said facemask.

2. In an arrangement as defined in claim 1,

a push-rod connected to the top of said piston,

said push-rod extending beyond the other end of said sleeve forpermitting said piston to be manually moved between its upper and lowerpositions with said sleeve.

3. In an arrangement as defined in claim 1,

a closure cap covering the other end of said sleeve,

said closure cap being provided with a multiplicity of apertures whichpermit air from the atmosphere to be drawn into said sleeve,

said closure cap having a circular recess cut in the rim portion thereoffor accommodating the end of said bellows which is connected to the topof said sleeve.

4. In an arrangement as defined in claim 3,

a helical spring disposed between said closure cap and the top of saidpiston,

said helical spring being maintained under compression when said pistonis in its upper position and having insufi'icient force to displace saidpiston to its lower position whenever the pressure within said chamberis greater than the adjacent atmospheric pressure.

5. An anti-sutfocant safety valve for an oxygen supply system of thetype wherein oxygen from a supply source flows into a supply lineleading into the interior of a facemask comprising, in combination,

a chamber;

a sleeve extending upwardly from an exterior wall of said chamber withone end of said sleeve communicating with the interior of said chamber;

a piston accommodated within said sleeve;

said piston having a diameter that is less than the interior diameter ofsaid sleeve whereby an air passageway exists between the inner wall ofsaid sleeve and the rim of said piston;

an over-center, snap-acting switching mechanism mounted in said chamberand connected to said piston for displacing said piston between an upperand a lower position within said sleeve;

a flexible, tubular bellows disposed within said sleeve,

one end of said bellows being connected to an inner wall portion of saidsleeve adjacent the other end' thereof,

- 6 a the other end of said bellows terminating at a position which isslightly beyond the mid-point between the upper and lower positions ofsaid piston whereby said other end of said bellows contact said pistonto form an airtight seal therewith while .said piston is in its upperposition and as it moves to said. position slightly beyond saidmid-point and whereby said bellows is spaced from said piston when saidpiston is in its lower position; and means for coupling said chamber tosaid supply line and said supply source whereby whenever a negativepressure is created in said chamber in response to the inhalationeiforts of an individual wearing said facemask said piston is drawndownwardly from its upper position until said over-center, snap-actingswitching mechanism suddenly activates it to its lower position wherebyair from the atmosphere can thereafter be drawn through said sleeve andinto said chamber for use by said individual.

References Cited by the Examiner UNITED STATES PATENTS 1,610,500 12/26Eggleston 25 l280 X 2,416,411 2/47 Sharbaugh et a1 128146 2,598,525 5/52Fox 128-142 X 3,092,104 6/63 Cassidy l28142 30 RICHARD A. GAUDET,Primary Examiner.

1. AN ANTI-SUFFOCANT SAFETY VALVE FOR AN OXYGEN SUPPLY SYSTEM OF THETYPE WHEREIN OXYGEN FROM A SUPPLY SOURCE ENTERS A SUPPLY LINE LEADINGINTO THE INTERIOR OF A FACEMASK COMPRISING, IN COMBINATION, A CHAMBER; ASLEEVE CONNECTED TO AN EXTERIOR WALL OF SAID CHAMBER AND HAVING ONE ENDTHEREOF COMMUNICATING WITH THE INTERIOR OF SAID CHAMBER; A PISTONPOSITIONED WITHIN SAID SLEEVE AND HAVING A DIAMETER LESS THAN THEINTERIOR DIAMETER OF SAID SLEEVE: AN "OVER-CENTER," SNAP-ACTINGSWITCHING MECHANISM CONNECTED TO SAID CHAMBER AND TO SAID PISTON FORMOVING SAID PISTON BETWEEN AN UPPER AND LOWER POSITION WITHIN SAIDSLEEVE; A BELLOWS OPEN AT BOTH ENDS THEREOF; SAID BELLOWS HAVING ONE ENDTHEREOF CONNECTED TO THE TOP OF SAID SLEEVE AND THE OTHER END EXTENDINGDOWNWARDLY TO A POSITION SLIGHTLY BEYOND THE MID-POINT BETWEEN THE UPPERAND LOWER POSITIONS OF SAID PISTON WHEREBY SAID BELLOWS CONTACTS SAIDPISTON TO FORM AN AIRTIGHT SEAL THEREWITH FROM THE UPPER POSITION OFSAID PISTON TO A POSITION SLIGHTLY BEYOND SAID MIDPOINT AND IS SPACEDFROM SAID PISTON WHEN SAID PISTON IN IN ITS LOWER POSITION, AND MEANSDEFINING AN AIR PASSAGEWAY BETWEEN SAID CHAMBER, SAID SUPPLY SOURCE ANDSAID SUPPLY LINE WHEREBY WHENEVER A NEGATIVE PRESSURE IS CREATED IN SAIDSUPPLY LINE IN RESPONSE TO THE INHALATION EFFORTS OF AN INDIVIDUALWEARING SAID FACEMASK, SAID PISTON IS DRAWN DOWNWARDLY FROM ITS UPPERPOSITION UNTIL SAID "OVER-CENTER," SNAP-ACTING SWITCHING MECHANISMSUDDENLY ACTIVATES IT TO ITS LOWER POSITION WHEREBY AIR FROM THEATMOSPHERE CAN THEREAFTER BE DRAWN THROUGH SAID SLEEVE AND INTO SAIDCHAMBER FOR USE BY THE INDIVIDUAL WEARING SAID FACEMASK.